1. Field of the Invention
This invention generally relates to detecting defects on a wafer. Certain embodiments relate to detecting defects on a wafer using a two-dimensional scatter plot generated from output generated by different optics modes of an inspection system.
2. Description of the Related Art
The following description and examples are not admitted to be prior art by virtue of their inclusion in this section.
Inspection processes are used at various steps during a semiconductor manufacturing process to detect defects on wafers to promote higher yield in the manufacturing process and thus higher profits. Inspection has always been an important part of fabricating semiconductor devices such as ICs. However, as the dimensions of semiconductor devices decrease, inspection becomes even more important to the successful manufacture of acceptable semiconductor devices because smaller defects can cause the devices to fail. For instance, as the dimensions of semiconductor devices decrease, detection of defects of decreasing size has become necessary since even relatively small defects may cause unwanted aberrations in the semiconductor devices.
Some currently available inspection systems are configured to inspect a wafer with more than one detection channel, to detect defects on the wafer by separately processing the data acquired by each of the channels, and to classify the defects by separately processing the data acquired by each of the channels. The defects detected by each of the individual channels may also be further processed separately, for example, by generating different wafer maps, each illustrating the defects detected by only one of the individual channels. The defect detection results generated by more than one channel of such a system may then be combined using, for example, Venn addition of the individual wafer maps. Such previously used inspection methods, therefore, do not leverage the output generated by the inspection system at the pixel level, but rather combine the results at the wafer map level as the final result.
Accordingly, it would be advantageous to develop methods and systems for detecting defects on a wafer that make better use of the inspection system output to provide increased defect detection sensitivity.